The mission of the Mass Spectrometry Core (MSC) is to provide cost effective, state-of-the-art mass spectrometry instrumentation to members of the Research Center for Pharmacology and Drug Toxicology. These instruments will be used for rapid identification of agents responsible for inflammation, for structural analysis of oxidized lipids and for qualitative and quantitative assays of eicosanoids and drug metabolites in physiologic fluids. The Core has two triple quadrupole LC/MS instruments, a time-of-flight LC/MS instrument, four GC/MS systems and a matrix assisted laser desorption ionization (MALDI) mass spectrometer. Laboratory personnel assist users in GC/MS and LC/MS methods development, participate in experimental design, develop standard operating procedures, maintain QC records on instrument performance and maintenance history, perform routine assays for investigators and train students and fellows in the theoretical and practical aspects of mass spectrometry. The Core is run as an open-access facility in which users are expected to prepare their own samples and to operate the instruments. Administrative staff monitors the use of the instrument facilities by investigators and prepares reports on utilization for the Center director. The six research projects described in this proposal have each identified mass spectrometry as a necessary component of their research. GC/MS services are requested by the principle investigators of five of the projects, and LC/MS is requested by four of the projects. Routine Core services fall into four general areas; (1) determination of eicosanoid concentration by isotope dilution GC/MS, (2) determination of molecular structure by tandem LC/MS and tandem GC/MS, (3) quantitation of drug metabolites by GC/MS or LC/MS and (4) tandem GC/MS analysis of novel eicosanoid oxygenation To expand the range of services offered by the MS Core, funds are requested for the purchase of a tandem instrument, which will be cost-shared equally with the University.